In mobile communication systems such as UMTS (Universal Mobile Telecommunication System) and cdma2000, channel quality indicator (CQI) reports are transmitted from a mobile station (MS) to a base station (BS) in order to assist the BS in selecting an appropriate transmission format (e.g. modulation and coding scheme) for downlink data transmissions, and/or to assist the BS in scheduling data transmissions to different MSs.
The following mechanisms for transmitting CQI reports are known:
a) configuring the MS to send a regular periodic CQI report (e.g. between every 2 ms and every 160 ms in the High Speed Downlink Packet Access (HSDPA) service of UMTS), by sending a signalling message to the MS at the start of the periodic reporting, and another signalling message when the period of the reporting is to be changed or the reporting terminated;
b) configuring the MS to send a single CQI report after each received data packet;
c) configuring the MS to send a single CQI report after each negatively-acknowledged data packet;
d) using a signalling message to request a single one-off CQI report from the MS.